476 
BULLETIN OF THE UNITED STATES FISH COMMISSION 
Fig. 113. Outlines of another larva of the same ovary showing Kupffer’s vesicle. 
Fig. 114. Outlines of a median section of another larva of the same stage. 
Plate CVIII. 
Figs. 115-118. Sections further illustrating the hypoblastic areas of the stage represented in fig. 76. 
Hypoblast shaded. 
Fig. 115 is a section parallel to fig. 15, and much more lateral in its position, showing the relation of 
the hypoblast (shaded) to the auditory thickening. 
Fig. 116. A cross-section passing just above the anterior end of the chorda. It cuts the auditory 
thickening at “an” and the lateral gill-pouches. See aa' in fig. 76. 
Fig. 117. Another section of the same series through the middle of the body, showing the floor cells 
of the alimentary tract. See W jn fig. 76. 
Fig. 118. Another section through Kupffer’s vesicle. See cc' in fig. 76. 
Figs. 119-124. Outlines of 6 sections from a larva slightly older than fig. 76. The larva was cut 
into 46 sections. Fig. 119 represents the 36th section from behind; fig. 120, the 35th; fig. 
121, the 34th ; fig. 122, the 31st ; fig. 123, the 18th ; and fig. 124, the 13th section. The lumen 
of the intestine is just forming. Figs. 119-122 represent the gill region, the remainder the 
posterior region ; fig. 124 showing especially well the wide potential slit of the intestine 
just in front of Kupffer’s vesicle. 
Figs. 125-127. Three sections of the intestine of another larva from the same ovary between the 
regions represented by figs. 122 and 123. 
Plate CIX. 
Figs. 128-135. Eight cross-sections of a larva in the stage represented by fig. 77. The larva was cut 
into 59 sections. The figures represent the following sections from in front backward. 
Figures. 
i Section. 
128 
12 
129 
17 
130 
18 
131 
22 
132 
24 
133 
41 
134 
46 
135 
53 
The sections are somewhat oblique, so that the dextral half of the figures are further 
forward than the sinistral. Figs. 129, 132, and 133 are magnified less than the others. 
Fig. 128. The section passes through the left hyobranchial slit, the auditory thickening, and the heart, 
which is still a solid mass of mesoblast cells. 
Fig. 129. The alimentary canal just behind the gill invagination. 
Fig. 130. The next section, the sinistral half of the alimentary tract, solid. 
Fig. 131. A section through the solid oesophagus, the floor cells distinct from the roof cells 
Fig. 132. Outlines of a section a little farther back. 
Fig. 133. Outlines of the intestine much farther back. 
Fig. 134. Section through the widest part of the intestine and through Kupffer’s vesicle. 
Fig. 135. Section through the neurenteric portion of Kupflfer’s vesicle. 
Plate CX. 
Fig. 136. Sagittal section of a larva about 1 mm. long and with about twenty protovertebrae ; some- 
what diagrammatic, from a number of sections. The heart is shortened and the pericardial 
chamber reduced by reagents. A large number of spermatozoa are seen in the intestine. 
The yolk has been eaten into. The auditory capsule is much nearer the surface and has 
been added to show the relation of the parts at this time. 
Fig. 137. Details of the gill region near the side of a similar larva. 
